1. Field of the Invention
The present invention provides curable compositions, which cure upon exposure to ultraviolet (“UV”) light and/or heat by a thiol-ene mechanism. The compositions include components having alkenyl (or “ene”) functionality and components having thiol functionality, which undergo thiol-ene curing. Also provided are methods of making the compositions.
2. Brief Description of Related Technology
UV-curable elastomers are used for a variety of applications, such as, for examples, adhesives and sealants. Known UV-curable elastomers, including acrylic elastomers, particularly elastomers derived from blends of polymers sold under the trade name VAMAC (available commercially from Dupont) and acrylate monomers, often involve a number of processing concerns. In particular, such UV-curable elastomers generally require the use of rubber mills for compounding and hot melt equipment for dispensing and application. The application temperature may range anywhere from 90-170° C. Moreover, such systems are inhibited by air and require long exposures to high intensity light to ensure cure. These requirements add costs to the process and also prevent the use of thermal-initiated curing.
There is a need therefore for UV and/or heat curable elastomers that proceed via a different curing mechanism. In particular, there is a need for curable compositions based on thiol-ene chemistry that can be used for a variety of applications, particularly as sealants for in-place gasketing applications.